The present invention relates generally a receptacle and, more particularly, to a receptacle for use in conjunction with a device such as a vessel. The vessel can be incorporated, for example, into a refrigeration system.
A refrigeration system comprises a compressor which conveys compressed refrigerant in a gas state to a condenser where it is cooled into a liquid state and passed to an evaporator. In the evaporator, the now-liquid refrigerant evaporates into a gas thereby absorbing heat energy and cooling an associated area. Thereafter, the now-gas refrigerant flows back to the compressor to repeat the cycle. A regulator supplies oil to the crankcase of the compressor to lubricate its moving parts and to enhance sealing of its piston for efficient compressing. An accumulator/separator can be provided to separate the oil (which becomes atomized and mixed with the refrigerant in the compressor) from the vapor so that only refrigerant is conveyed to the condenser input. A muffler can also be provided either upstream or downstream of the compressor to reduce noise levels.
A regulator, an accumulator, and a muffler each typically comprise a vessel having inlet/outlet fittings for connection to the appropriate system line. For example, the regulator can have an inlet fitting in it top end wall for connection to a supply line of an oil reservoir. The accumulator can have an inlet fitting in its top end wall for connection to the compressor discharge line, an outlet fitting in its top end wall for connection to the condenser input line, and an outlet fitting in its bottom end wall for connection to a drain line to the oil reservoir. If the muffler is a suction muffler (i.e., upstream of the compressor), it can have an inlet fitting on its top wall for connection to the evaporator output line and an outlet fitting on its top wall for connection to the compressor suction line. If the muffler is a discharge muffler (i.e., downstream of the compressor), it can have an inlet fitting in its top wall for connection to the compressor discharge line and an outlet fitting in its bottom wall for connection to the condenser input line. In any event, the interface of the inlet/outlet fittings in the top or bottom walls create joints in the vessel""s construction.
Regulators, accumulators, and mufflers are typically mounted on or near the compressor whereby compressor-generated vibration is transmitted thereto. This vibration can stress any susceptible joints in the vessel construction and the stress level can be sufficient to fatigue and damage the individual components.
In some applications, it may be desirable to attach a device such as a pressure relief valve or a refrigerant line onto the vessel using a threaded fitting. Accordingly, the vessel can be provided with a compatible inlet fitting to receive the device. The inlet fitting should have a sealing surface and a threaded protrusion to mate with the device. However, known techniques for forming such an inlet fitting have proved to be problematic.
One technique for forming the fitting includes extruding a metal blank to form the inlet fitting. The process of extrusion typically includes piercing a hole in the blank and then flanging the metal surrounding the hole to produce a protrusion of metal which extends longitudinally from the parent metal of the blank. The length of the protrusion is limited by the strain capacity of the metal, which, if exceeded, will cause the edge of the protrusion to fracture or split. In addition, extrusion of the metal thins the thickness of the protrusion wall, especially at the end of the protrusion and where the protrusion meets the parent metal. Therefore, the resultant protrusion will have a tapered wall thickness and will have a relatively large radius where the protrusion meets the parent metal. These characteristics are not well suited to receiving a threaded fitting.
According, there is a need in the art for a vessel having an inlet fitting adapted to receive a threaded device, such as a pressure relief valve or a refrigerant line. There is also a need in the art for techniques for forming such an inlet fitting.
According to one aspect of the invention, the invention is directed to a vessel for use in a refrigeration system. The vessel includes a vessel body and at least one end wall for closing the vessel body, the end wall having a threaded receptacle. The threaded receptacle is configured to accept a threaded fitting and the threaded receptacle includes: an annular sealing surface for engaging a corresponding surface of the fitting, the sealing surface formed on a first side of the end wall; and a threaded surface defined by an inside wall of an annular protrusion, the annular protrusion having a longitudinal axis disposed generally perpendicular to the sealing surface, and wherein the protrusion extends longitudinally from a second side of the end wall toward an interior of the vessel body.
According to another aspect of the invention, the invention is directed to a method of making a threaded receptacle. The method includes drawing a metal blank with a drawing punch to form an intermediate protrusion and thereby gathering metal for the sealing surface and annular protrusion; forming a hole in a bottom of the drawn intermediate protrusion; capturing the metal blank in a capture die having a first portion with a stop surface against which the sealing surface is formed and a second portion defining an opening for controlling formation of an outside diameter of the annular protrusion; and reflowing the drawn intermediate protrusion with a punch, the punch having a pilot for controlling the formation of an inside diameter of the annular protrusion and an engagement surface for engaging a distal edge of the intermediate protrusion.
These and other features of the invention are fully described herein and particularly pointed out in the claims. The following description and drawings set forth in detail a certain illustrative embodiment of the invention, this embodiment being indicative of but one of the various ways in which the principles of the invention may be employed.